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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 81 · 40 questions
TalentJR

How to do it in your head (Round, then work): Round each number: 2-digit numbers to the nearest ten, 3-digit numbers to the nearest hundred. Do the easy sum with the round numbers. Choose the option closest to your estimate.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 74 × 77? (a) 56000 (b) 560 (c) 5600
  2. 2.Best estimate of 56 × 84? (a) 48000 (b) 480 (c) 4800
  3. 3.Best estimate of 862 + 249? (a) 1300 (b) 1100 (c) 900
  4. 4.Best estimate of 342 + 181? (a) 500 (b) 700 (c) 300
  5. 5.Best estimate of 47 × 64? (a) 300 (b) 30000 (c) 3000
  6. 6.Best estimate of 498 + 498? (a) 1200 (b) 800 (c) 1000
  7. 7.Best estimate of 561 + 785? (a) 1600 (b) 1400 (c) 1200
  8. 8.Best estimate of 98 × 28? (a) 30000 (b) 300 (c) 3000
  9. 9.Best estimate of 50 × 19? (a) 1000 (b) 100 (c) 10000
  10. 10.Best estimate of 36 × 91? (a) 3600 (b) 36000 (c) 360
  11. 11.Best estimate of 98 × 21? (a) 20000 (b) 200 (c) 2000
  12. 12.Best estimate of 594 + 390? (a) 800 (b) 1200 (c) 1000
  13. 13.Best estimate of 743 + 724? (a) 1400 (b) 1600 (c) 1200
  14. 14.Best estimate of 58 × 67? (a) 42000 (b) 4200 (c) 420
  15. 15.Best estimate of 32 × 36? (a) 12000 (b) 1200 (c) 120
  16. 16.Best estimate of 574 + 606? (a) 1200 (b) 1400 (c) 1000
  17. 17.Best estimate of 51 × 98? (a) 500 (b) 5000 (c) 50000
  18. 18.Best estimate of 395 + 384? (a) 600 (b) 800 (c) 1000
  19. 19.Best estimate of 71 × 76? (a) 560 (b) 56000 (c) 5600
  20. 20.Best estimate of 24 × 84? (a) 16000 (b) 1600 (c) 160
  21. 21.Best estimate of 41 × 90? (a) 360 (b) 36000 (c) 3600
  22. 22.Best estimate of 91 × 21? (a) 1800 (b) 180 (c) 18000
  23. 23.Best estimate of 32 × 96? (a) 300 (b) 30000 (c) 3000
  24. 24.Best estimate of 310 + 128? (a) 600 (b) 400 (c) 200
  25. 25.Best estimate of 22 × 43? (a) 80 (b) 8000 (c) 800
  26. 26.Best estimate of 814 + 313? (a) 1300 (b) 1100 (c) 900
  27. 27.Best estimate of 64 × 76? (a) 4800 (b) 480 (c) 48000
  28. 28.Best estimate of 33 × 74? (a) 21000 (b) 2100 (c) 210
  29. 29.Best estimate of 81 × 61? (a) 48000 (b) 4800 (c) 480
  30. 30.Best estimate of 632 + 654? (a) 1500 (b) 1300 (c) 1100
  31. 31.Best estimate of 182 + 451? (a) 900 (b) 700 (c) 500
  32. 32.Best estimate of 368 + 595? (a) 1200 (b) 1000 (c) 800
  33. 33.Best estimate of 354 + 380? (a) 600 (b) 1000 (c) 800
  34. 34.Best estimate of 27 × 90? (a) 27000 (b) 270 (c) 2700
  35. 35.Best estimate of 31 × 76? (a) 24000 (b) 240 (c) 2400
  36. 36.Best estimate of 56 × 21? (a) 120 (b) 12000 (c) 1200
  37. 37.Best estimate of 29 × 47? (a) 150 (b) 1500 (c) 15000
  38. 38.Best estimate of 180 + 744? (a) 900 (b) 700 (c) 1100
  39. 39.Best estimate of 37 × 53? (a) 200 (b) 20000 (c) 2000
  40. 40.Best estimate of 792 + 585? (a) 1600 (b) 1400 (c) 1200

Answer key

  1. 5600
  2. 4800
  3. 1100
  4. 500
  5. 3000
  6. 1000
  7. 1400
  8. 3000
  9. 1000
  10. 3600
  11. 2000
  12. 1000
  13. 1400
  14. 4200
  15. 1200
  16. 1200
  17. 5000
  18. 800
  19. 5600
  20. 1600
  21. 3600
  22. 1800
  23. 3000
  24. 400
  25. 800
  26. 1100
  27. 4800
  28. 2100
  29. 4800
  30. 1300
  31. 700
  32. 1000
  33. 800
  34. 2700
  35. 2400
  36. 1200
  37. 1500
  38. 900
  39. 2000
  40. 1400

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